nl80211/mac80211: mesh: add mesh path change count to mpath info

Expose path change count to destination in mpath info
Signed-off-by: Julan Hsu <julanhsu@google.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -1439,7 +1439,8 @@ enum mpath_info_flags {
 	MPATH_INFO_DISCOVERY_TIMEOUT	= BIT(4),
 	MPATH_INFO_DISCOVERY_RETRIES	= BIT(5),
 	MPATH_INFO_FLAGS		= BIT(6),
-	MPATH_INFO_HOP_COUNT		= BIT(7)
+	MPATH_INFO_HOP_COUNT		= BIT(7),
+	MPATH_INFO_PATH_CHANGE		= BIT(8),
 };
 
 /**
@@ -1460,6 +1461,7 @@ enum mpath_info_flags {
  *	changes, i.e. when a station is added or removed, so that
  *	userspace can tell whether it got a consistent snapshot.
  * @hop_count: hops to destination
+ * @path_change_count: total number of path changes to destination
  */
 struct mpath_info {
 	u32 filled;
@@ -1471,6 +1473,7 @@ struct mpath_info {
 	u8 discovery_retries;
 	u8 flags;
 	u8 hop_count;
+	u32 path_change_count;
 
 	int generation;
 };

include/uapi/linux/nl80211.h

@@ -3288,8 +3288,9 @@ enum nl80211_mpath_flags {
  * @NL80211_MPATH_INFO_DISCOVERY_TIMEOUT: total path discovery timeout, in msec
  * @NL80211_MPATH_INFO_DISCOVERY_RETRIES: mesh path discovery retries
  * @NL80211_MPATH_INFO_HOP_COUNT: hop count to destination
+ * @NL80211_MPATH_INFO_PATH_CHANGE: total number of path changes to destination
  * @NL80211_MPATH_INFO_MAX: highest mesh path information attribute number
- *	currently defind
+ *	currently defined
  * @__NL80211_MPATH_INFO_AFTER_LAST: internal use
  */
 enum nl80211_mpath_info {
@@ -3302,6 +3303,7 @@ enum nl80211_mpath_info {
 	NL80211_MPATH_INFO_DISCOVERY_TIMEOUT,
 	NL80211_MPATH_INFO_DISCOVERY_RETRIES,
 	NL80211_MPATH_INFO_HOP_COUNT,
+	NL80211_MPATH_INFO_PATH_CHANGE,
 
 	/* keep last */
 	__NL80211_MPATH_INFO_AFTER_LAST,

net/mac80211/cfg.c

@@ -1746,7 +1746,8 @@ static void mpath_set_pinfo(struct mesh_path *mpath, u8 *next_hop,
 			MPATH_INFO_DISCOVERY_TIMEOUT |
 			MPATH_INFO_DISCOVERY_RETRIES |
 			MPATH_INFO_FLAGS |
-			MPATH_INFO_HOP_COUNT;
+			MPATH_INFO_HOP_COUNT |
+			MPATH_INFO_PATH_CHANGE;
 
 	pinfo->frame_qlen = mpath->frame_queue.qlen;
 	pinfo->sn = mpath->sn;
@@ -1767,6 +1768,7 @@ static void mpath_set_pinfo(struct mesh_path *mpath, u8 *next_hop,
 	if (mpath->flags & MESH_PATH_RESOLVED)
 		pinfo->flags |= NL80211_MPATH_FLAG_RESOLVED;
 	pinfo->hop_count = mpath->hop_count;
+	pinfo->path_change_count = mpath->path_change_count;
 }
 
 static int ieee80211_get_mpath(struct wiphy *wiphy, struct net_device *dev,

net/mac80211/mesh.h

@@ -94,6 +94,7 @@ enum mesh_deferred_task_flags {
  * @last_preq_to_root: Timestamp of last PREQ sent to root
  * @is_root: the destination station of this path is a root node
  * @is_gate: the destination station of this path is a mesh gate
+ * @path_change_count: the number of path changes to destination
  *
  *
  * The dst address is unique in the mesh path table. Since the mesh_path is
@@ -124,6 +125,7 @@ struct mesh_path {
 	unsigned long last_preq_to_root;
 	bool is_root;
 	bool is_gate;
+	u32 path_change_count;
 };
 
 /**

net/mac80211/mesh_hwmp.c

@@ -479,6 +479,8 @@ static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
 		}
 
 		if (fresh_info) {
+			if (rcu_access_pointer(mpath->next_hop) != sta)
+				mpath->path_change_count++;
 			mesh_path_assign_nexthop(mpath, sta);
 			mpath->flags |= MESH_PATH_SN_VALID;
 			mpath->metric = new_metric;
@@ -523,6 +525,8 @@ static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
 		}
 
 		if (fresh_info) {
+			if (rcu_access_pointer(mpath->next_hop) != sta)
+				mpath->path_change_count++;
 			mesh_path_assign_nexthop(mpath, sta);
 			mpath->metric = last_hop_metric;
 			mpath->exp_time = time_after(mpath->exp_time, exp_time)

net/wireless/nl80211.c

@@ -5830,7 +5830,10 @@ static int nl80211_send_mpath(struct sk_buff *msg, u32 portid, u32 seq,
 			pinfo->discovery_retries)) ||
 	    ((pinfo->filled & MPATH_INFO_HOP_COUNT) &&
 	     nla_put_u8(msg, NL80211_MPATH_INFO_HOP_COUNT,
-			pinfo->hop_count)))
+			pinfo->hop_count)) ||
+	    ((pinfo->filled & MPATH_INFO_PATH_CHANGE) &&
+	     nla_put_u32(msg, NL80211_MPATH_INFO_PATH_CHANGE,
+			 pinfo->path_change_count)))
 		goto nla_put_failure;
 
 	nla_nest_end(msg, pinfoattr);